Those words can be understood as uttered out of great respect towards his father King Dasaratha.
The preceding and succeeding slokas give clue to us, as to how much respect Sri Rama had towards his father.
अलीकम् मानसम् तु एकम् ह्ऱ्दयम् दहति इव मे | स्वयम् यन् न आह माम् राजा
भरतस्य अभिषेचनम् || २-१९-६
"My heart is burning indeed with one sorrowful feeling that king
himself has not informed me about Bharata's coronation."
किम् पुनर् मनुज इन्द्रेण स्वयम् पित्रा प्रचोदितः | तव च प्रिय काम
अर्थम् प्रतिज्ञाम् अनुपालयन् || २-१९-८
"Being directed by king, who is my father himself, how much more
should I tell that I can give everything to Bharata, duly obeying
father's promise to fulfil your beloved desire."